U.S. patent number 5,984,534 [Application Number 08/823,388] was granted by the patent office on 1999-11-16 for method and device for waveguide connection.
This patent grant is currently assigned to Telefonaktiebolaget LM Ericsson. Invention is credited to H.ang.kan Elderstig, Olle Larsson, Ove Ohman, Goran Palmskog.
United States Patent |
5,984,534 |
Elderstig , et al. |
November 16, 1999 |
Method and device for waveguide connection
Abstract
Replicated polymeric microstructures have been used in the
fabrication of optofiber waveguide connections, with the intention
of simplifying the production of such connections, and therewith
greatly reduce manufacturing costs. Fabrication is commenced from a
silicon chip in which there has been etched grooves whose
cross-sectional shape has been adapted to accommodate waveguides,
such as optofibers. Firstly, the silicon chip is replicated, by
plating the silicon chip with nickel for instance. The replication
then serves as a model for producing a plastic copy of the silicon
chip. This method of manufacture is able to produce waveguide
accommodating grooves (2), such as optofiber accommodating grooves,
to a very high degree of accuracy. Furthermore, the method provides
a high degree of freedom in the configuration of the grooves, and
also enables branched grooves for receiving branched fibres to be
produced. The waveguide connection can then be used with a
waveguide, such as an optofiber, together with a light transmitter
or light receiver.
Inventors: |
Elderstig; H.ang.kan (Bromma,
SE), Larsson; Olle (Stockholm, SE),
Palmskog; Goran (Uppsala, SE), Ohman; Ove
(Uppsala, SE) |
Assignee: |
Telefonaktiebolaget LM Ericsson
(Stockholm, SE)
|
Family
ID: |
20401933 |
Appl.
No.: |
08/823,388 |
Filed: |
March 24, 1997 |
Foreign Application Priority Data
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Mar 25, 1996 [SE] |
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9601137 |
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Current U.S.
Class: |
385/90;
385/88 |
Current CPC
Class: |
G02B
6/4246 (20130101); G02B 6/4243 (20130101); G02B
6/3696 (20130101); G02B 6/4201 (20130101); G02B
6/4214 (20130101); G02B 6/3636 (20130101); G02B
6/4239 (20130101); G02B 6/3652 (20130101); H01L
2224/11 (20130101); G02B 6/3692 (20130101); G02B
6/4238 (20130101) |
Current International
Class: |
G02B
6/42 (20060101); G02B 6/36 (20060101); G02B
006/36 () |
Field of
Search: |
;385/90,89,88,91,83,65 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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WO93/21550 |
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Oct 1993 |
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WO |
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WO94/28449 |
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Dec 1994 |
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WO |
|
Other References
International-Type Search Report re SE 96/01223 Date of mailing of
Search Report: Dec. 11, 1996. .
R. Klein et al., "Silicon Micromachining for Micro-Replication
Technologies", Electronics Letters. vol. 30, No. 20, pp. 1672-1674
(Sep. 1994)..
|
Primary Examiner: Bovernick; Rodney
Assistant Examiner: Kang; Ellen E.
Attorney, Agent or Firm: Burns, Doane, Swecker & Mathis,
L.L.P.
Claims
What is claimed:
1. A device for connecting at least one waveguide to one of an
optical transmitter and an optical receiver, said device comprising
an alignment structure having a pattern of grooves for
accommodating a branched waveguide, wherein the alignment structure
further comprises at least one cooling means and a means for
transmitting light between the waveguide and said one of the
optical transmitter and the optical receiver such as to connect at
least one of the optical transmitter and the optical receiver to
the device and to said waveguide present in the alignment
structure.
2. A device according to claim 1 wherein said cooling means is a
cooling circulating passageway.
3. A device according to claim 1 wherein said cooling means is a
metal-filled recess.
Description
FIELD OF INVENTION
The present invention relates to a method of providing at least one
waveguide connection, and to a device for connecting at least one
waveguide to an optical transmitter or to an optical receiver, for
instance.
BACKGROUND OF THE INVENTION
Known in the art are various types of waveguide connections that
have been fabricated with etched silicon chips as
substrate/carrier. Silicon chips, however, are expensive to
produce, particularly large silicon chips, wherewith a silicon chip
will preferably not be larger than 2.times.2 mm. Silicon chips are
liable to break under the high pressures to which they subjected
when pressing waveguide connections, besides being easily worn.
Other types of waveguide connections include laboratory produced
connections. These waveguide connections are also expensive to
produce with the precision required. In order to enable fibreoptic
connectors to be used on a large scale, said connectors must be
able to compete strongly with existing solutions, especially with
regard to cost.
SUMMARY OF THE INVENTION
Replicated polymeric microstructures have been used in the
fabrication of said waveguide connections, with the intention of
simplifying the production of such connections, for instance
optofibre connections, and therewith greatly reduce manufacturing
costs. Fabrication is commenced from a silicon chip in which there
has been etched grooves whose cross-sectional shape has been
adapted to accommodate waveguides, such as optofibres. Firstly, the
silicon chip is replicated, by plating the silicon chip with nickel
for instance. The replication then serves as a model for producing
a plastic copy of the silicon chip. This method of manufacture is
able to produce waveguide accommodating grooves, such as optofibre
accommodating grooves, to a very high degree of accuracy.
Furthermore, the method provides a high degree of freedom in the
configuration of the grooves, and also enables branched grooves for
receiving branched fibres to be produced. The waveguide connection
can then be used with a waveguide, such as an optofibre, together
with a light transmitter or light receiver.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a simplified cross-sectional view taken from one side of
an inventive waveguide connector with an optofibre.
FIG. 2 illustrates from above the manner in which grooves and
optofibres can be disposed in an inventive waveguide connector.
FIGS. 3A and B are simplified cross-sectional views of a coupling
means for waveguide connections having a cover member that includes
different groove configurations in accordance with the
invention.
FIG. 4 illustrates a branching pattern for a waveguide connection
in accordance with the invention.
DETAILED DESCRIPTION OF EMBODIMENTS
With the intention of illustrating the special features of the
invention, there will first be described a method of manufacture of
an inventive fibre optic receiver module, where the actual carrier
can be produced with high precision from a plastic material and
with an alignment structure useful with MM/SM-splicing of
optofibres. Low cost optical components can be produced from
plastic materials with the aid of replication. Practically all
configurations that are possible to produce technically on silicon
can be replicated on plastic material. Since replication is not in
itself an expensive process, there is available an economic leeway
which will enable the use of advanced manufacturing equipment,
process equipment and test equipment in tool manufacture, for
instance micromechanics in silicon, spark machining, LIGA
techniques, electron beam lithography, and so on.
In this context, components replicated in polymeric material can be
used as carriers for semiconductor components, such as detectors,
and for positioning optical fibres. Replication in polymeric
material is a low cost technique that can achieve great
significance in packaging structures and encapsulation with
concentration on "Data Comm" for instance.
Distinct from silicon, plastic has good dielectric properties. The
plastic may be transparent, which can be beneficial in the case of
integrated optical applications. Plastic is cheaper to use than
silicon. Good optical, electrical and mechanical properties can
also be combined when replicating the aforesaid components.
Replicated polymeric substrates 1 can be used in the construction
of fibre optic transmitter/receiver modules having an alignment
structure such as fibre aligning grooves 2, optofibres 3 and
semiconductor components 4, such as PIN diodes, LEDs, lasers,
VCSELs, amplifiers, drive electronics, integrated circuits,
memories, and so on; see FIGS. 1 and 2. The polymeric substrate may
form an optical backplane that includes internal and external fibre
connections. The substrate may also have deposited thereon an
oxide, a nitride or some other appropriate material that will
protect the plastic against the effect of chemicals. The substrate
may also include electric conductors 5, which may be comprised of
patterned or embossed metal, for chip connection for instance. The
optofibres 3 intended for the transmission of light between
different connections and said components may be glued firmly to
the substrate 1 with an electrically conductive glue 6, for
instance. Alternatively, the components may be fastened to the
substrate with the aid of a eutectic Pb/Sn, for instance. Light can
be arranged to be reflected onto a detector surface 8 from a mirror
7 provided at the end of a fibre alignment groove 8, said mirror
being obtained by metalizing the surface of the substrate 1 for
instance, or to be reflected from a surface emitting component into
the fibre. The mirror 7 will preferably slope at an angle of
45.degree. to the substrate surface. Transmitter and receiver
components may also be arranged in arrays, such as a row of eight
such components on one and the same unit. The grooves are
conveniently spaced at a pitch of 0.250 mm for instance, so as to
prevent interaction between fibres in respective fibre alignment
grooves.
The active components, such as splicing/coupling means, may be
protected by a polymeric material, a silicon elastomer, or may be
protected by a glued-on or welded cover member 9 that affords space
for or includes cavities for accommodating the components. In
addition to its protective function, the cover member of a coupling
means as illustrated in cross-section in FIGS. 3A and B will also
function to fixate and hold the fibres 3 firmly on the substrate 1.
The substrate 1 may include at least one passageway 10 through
which coolant can circulate to cool hot electronic chips. The
substrate may also include a recess or a hole 11 that is filled
with plated metal to improve cooling. The substrate may also
include guide-pin receiving holes 12 for connection to an MT
device.
The cover member 9 of the waveguide connection may be fastened to
the substrate 1 by ultrasonic welding 13 or may be glued firmly
thereto either before or after inserting and aligning the
optofibres. The glue used will preferably have a refractive index
that matches the refractive index of other equipment.
When manufacturing a waveguide connection with the aid of masks, a
V-groove alignment structure is first etched in a silicon chip, for
instance by wet etching in 70.degree. KOH, wherewith the geometry
of the V-grooves has been adapted to match a received waveguide,
such as an optofibre. A copy of the structured silicon chip is then
created by electroplating, with nickel for instance, wherein the
resultant nickel replicate is then used as a mould in the following
injection moulding and heat embossment of a plastic material, such
as polycarbonate (PC) or polymethyl methacrylate (PMMA), for
instance. The resultant hot-embossed substrate will have the same
configuration as the original silicon chip. It has been possible to
replicate polycarbonate substrates with a diameter of 80 mm from
silicon-etched microstructures with good replication and with cycle
times of less than twenty seconds.
The surface of the polycarbonate was then metalized by sputtering
with TiW and Au to a respective thickness of 500 .ANG. with respect
to TiW and of 2000 .ANG. with respect to Au. The metals are able to
function both as an electric conductor, a cooler, and as a mirror.
Two separate contacts can be created on each chip, by sawing a
shallow groove in the polycarbonate/chip.
Optical multimode fibres 3 comprised of quartz are then glued
firmly 6 into the V-grooves 2 provided in the chip, such that the
ends of the fibres lie in front of the sloping mirror, said mirror
being able to reflect light from the fibre up onto a component
surface.
Alternatively, microprocessed silicon substrates may be used as
inserts directly in an injection moulding press, with the advantage
of obtaining a short manufacturing chain. However, cracked silicon
moulds are liable to create a problem in the case of this latter
alternative, and it is often difficult to trim-in the system,
resulting in incomplete replication, among other things. However,
the greatest drawback is that in order for the silicon structure to
function as a mould, the structure must consist of the negative of
the article to be injection-moulded, which creates
process/technical difficulties and/or constructional
limitations.
The method of producing waveguide connections in accordance with
the invention has certain similarities with the manufacture of
compact discs, wherein a disc can be injection-moulded in less than
five seconds and can contain information in the form of shallow
pits of less than one micrometer in depth. It has been found in
earlier trials that deep V-grooves are liable to crack silicon
chips that have a standard thickness of 500 .mu.m. A further
conceivable modification is to shield the lithographic pattern in
the periphery of a silicon carrier. In the absence of such a
shield, high punctiform loads may be created as the plastic is
extruded from the mould via the microstructure. On the other hand,
when injection-moulding polymeric substrates using silicon carriers
as a mould, conventional injection-moulding presses or compact disc
(CD) manufacturing injection-moulding presses can be used.
Alternatively, instead of placing optofibres, branched or straight,
in the grooves provided in the substrate, an appropriate plastic
material 17 may be placed between the substrate 1 and the cover
member 9, as shown in FIG. 3B. When pressing the cover member
against the substrate, this plastic material would essentially
fill-out the grooves in the substrate, said grooves having a
V-shape or any other suitable shape. It is possible that some of
the light-conducting plastic will be deposited between the planar
surfaces of the substrate and the cover member by this pressing
operation, although an effective light conducting function will be
ensured provided that the major part of the light conducting
plastic material 17 is deposited in the waveguide grooves.
FIG. 4 illustrates part of a substrate 1 having a groove 2 that
branches into two grooves 14 and 15, which may be appropriate in
some cases, wherein the different parts of the divided plastic or
the branched optofibre 16 may be adapted to transmit light energy
to or from a receiver or transmitter through the medium of a
mirror.
* * * * *